The present invention concerns an improved process for the manufacture of planar Schottky barrier diodes having a guard ring.
Such a structure is well known to the person skilled in the art. It forms the subject of many works and a description thereof is to be found inter alia in U.S. Pat. No. 3,463,971, filed on Apr. 17, 1967.
The advantage of such structures resides in that the barrier is formed by the very metal which serves as the output metal which facilitates the bonding of the output conductor of the diode. However, the use of a gold barrier often leads to a lack of reliability in time, which results essentially from an effect of diffusion of the gold in the silicon, which is of particular importance in the case of device operating at high temperature, such as power rectifiers. The deterioration of the barrier results from complex phenomena. It is probably promoted by the presence of impurities at the interface between the metal and the silicon. The present invention has essentially for its object to improve the process for the manufacture of gold-silicon barrier diodes with high stability in time, as well as enhanced stability at high temperature. The invention has also for its object to provide a process for the manufacture of guard ring Schottky diodes with high reverse voltages.